386 



[November, 1909. 



others the capsules bear high crinkled 

 ridges or wings. Curiously enough, those 

 trees which resemble the Oeara rubber 

 in the shape of the leaves usually differ 

 widely in the capsules and vice versa, 

 and when the whole aspect of the tree is 

 taken into consideration, there is never 

 any possibility of confusing one with 

 the other. 



The extraordinary variability in vege- 

 tative characters is of special interest as 

 indicating the likelihood of a similar 

 diversity between the yields of latex 

 produced by different tress. Of such a 

 variability, which is known to occur in 

 almost all rubber-yielding plants, we 

 have already some indications. 



In the case of a plant which is reputed 

 to afford a very appreciable yield of 

 rubber within three or four years of 

 planting, there can be no doubt of the 

 advisability of selecting the best yield- 

 ing trees for future propagation whether 

 from seed or by cuttings. Definite ex- 

 periments in this direction are in con- 

 templation at Peradeniya, but the experi- 

 ment is one which every planter can and 

 should carry out for himself. 



If propagation is by cuttings the pro- 

 duction from parents giving a good 

 yield of latex of offspring similarly 

 characterised is practically assured. 

 We have therefore every reason for 

 satisfaction in the result of expeiiments 

 already carried out by this method, for 

 we have found that cuttings up to two 

 inches in diameter will readily take root 

 and grow into healthy plants. A single 

 well-grown two-year-old tree will furnish 

 upwards of 200 cuttings. 



The chief defect which we have so 

 far noticed in this plant is its brittle- 

 ness, the tops being very liable to 

 damage by wind. In this way large 

 branches may be torn off, or the whole 

 tree broken down or uprooted. Some- 

 times it seems as if the mere weight 

 of the crown were too much for the 

 strength of the supporting structures, 

 the point of weakness being the place 

 where the first whorl of branches joins 

 the upright trunk. 



The twelve largest two-year-old trees 

 were tapped on alternate days from 

 October 7th until the end of the month. 

 Six of the trees were tapped to the wood 

 with the knife only, the remaining six 

 were tapped with the Northway knife 

 and pricker. The following amounts of 

 rubber (in grammes) were obtained in 

 ten days ' tapping :— 



548; 1*91; 3-46; 8"05; 1-78; 8 41 ; 

 •77 ; 5-63 ; 3*19 ; 4*00 ; 3-00 ; 4-06 ; 

 or 47*34 grammes of dry rubber from 

 twelve trees in ten days, in addition to 



25*35 grammes of scrap, or 72*69 grammes 

 of dry rubber altogether, which is equi- 

 valent to 2*6 ounces. 



Supposing that one cooly at 35 cents 

 can tap 120 trees in a day, the cost of 

 tapping works out at Rs. 2-20 per lb. 



As was|only to be expected, the yield of 

 rubber actually obtained is very small. 

 There is no reason, however, for sup- 

 posing that any other variety of rubber 

 would have given a larger yield at two 

 years old. 



In spite of the small number of trees 

 examined, the variations in yield are 

 well marked, more than ten times as 

 much rubber being yielded by the best 

 as by the poorest yielder. 



The only conclusion which can be 

 drawn from the above results is that a 

 commercial yield of rubber cannot be 

 expected in two years from planting, 

 and it is quite impossible to say what 

 the result after three, four or five years 

 may be. It seems probable, however, 

 that it will be possible to distinguish 

 good and bad yielding trees by experi- 

 ment within three years from planting. 

 Those who intend to give this species a 

 trial would therefore do well to plant up 

 a small area of 1 to 5 acres at once with 

 a view to further planting in two or 

 three years time. Then, if experiments 

 carried out on the trees at Peradeniya 

 indicate that Manihot dichotoma is 

 likely to turn out a commercial success 

 in Ceylon, the intending planter will be 

 in a position to cover a further area 

 with the offspring of plants selected for 

 their good bearing quality, using seed or 

 cuttings according to the result of our 

 further investigations. It should be 

 understood that this advice is given 

 without any promise that Manihot 

 dichotoma will prove a success in Ceylon 

 as a source of rubber ; but, if the species 

 does pi ove profitable, careful attention 

 to the selection of seed parents will 

 undoubtedly enhance the ultimate pro- 

 fits very materially. 



The following list of recent references 

 to Manihot dichotoma in the Tropical 

 Agriculturist may be of use to readers : — 



March 1908 ... New species of Manihot and 

 their Importance, p. 198. 

 April ,, ... Jequie Manicobar Rubber, 

 p. 298. 



May ,, ... Jequie Manicobar and its 



allies, p. 412. 

 June ,, ... Ceara or Manicobar rubber, 

 p. 519. 



October ,, ... Remarks on the cultiva- 

 tion, preparation and 

 yield of Manicobar, p. 317. 



April 1909 ... The New Manihots, p. 319. 



May The New Rubbers, p. 411. 



R. H. L. 



